<!DOCTYPE html>
<html lang="zh-cn">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>透明度</title>
    <style>
        #head02 {
            opacity: 0.5;
        }
    </style>
</head>

<body>
    <img id="head01" src="./img/head.jpg" alt="">
    <img id="head02" src="./img/head.jpg" alt="">
    <img id="head03" src="./img/head.jpg" alt="">
</body>

</html>